1. Technical Field
The present invention relates in general to lubrication devices and in particular to coupling devices for connecting a lubrication device to grease fittings. Still more particularly, the present invention relates to improving the connection and ease of use of the lubrication device with difficult to reach grease fittings.
2. Description of the Related Art
Lubrication is necessary for extending the life of mechanical equipment with metal components that rotate or slide against other metal components. Rotating shafts and other moving parts in equipment that contact metal components during operation, require some means of reducing friction to extend the life of the equipment. Preventive maintenance, including lubrication of the moving parts, is essential to prolong effective operation of mechanical equipment. Regular lubrication is extremely important because old grease in a joint or rotating assembly accumulates acids and particles over time. Particles and acid generally damage the surfaces that the grease is intended to protect. Usually, the new lubricant forces out the old, contaminated lubricant providing clean, contaminant-free lubricant to the moving parts.
Machinery requiring grease lubrication generally has grease ("zerk") fittings installed in suitable locations on the equipment to apply the grease. "Zerk" has become a generic term for a nipple type fitting used to provide a lubrication point on mechanical equipment with moving parts. The fitting is usually ball-shaped with a spring loaded one way valve for receiving lubricant. The lubricant, under pressure, overcomes the spring pressure against the one way valve so the target part may receive new lubricant. Generally, the procedure is to inject enough lubricant, under pressure, through the zerk fitting, to literally exchange the old, contaminant laden lubricant for clean lubricant.
Mechanical equipment such as vehicles, conveyor systems, elevators, etc., all require lubrication because of moving parts having metal to metal contact. In the design of most mechanical equipment, zerk fittings are located in strategic positions on a rotating or sliding part to enable regular lubrication of the critical points. Usually, a regular maintenance schedule is suggested by the manufacturer to keep the equipment properly lubricated. However, though most fittings are mounted on the machinery in relatively accessible locations, machine design sometimes dictates that the fitting be located in a hard to reach location. This causes the responsible operator to sometimes skip lubrication of a particular fitting. If a part is not properly and regularly lubricated, premature failure of a part could result. Also, even though the fitting may be serviced regularly, difficulty in accessing a fitting may cause the coupling on the applicator to incorrectly engage the zerk fitting. Lubricant then flows around the fitting causing misapplication and loss of lubricant.
A lubrication applicator ("grease gun") must have a female coupler that will engage the zerk fitting so that grease from the grease gun, under pressure, overcomes the spring tension of the one way valve in the zerk fitting. When properly connected, grease is transferred through the one way valve and does not leak grease around the fitting.
In most grease gun coupler attachments, the coupling has to be aligned correctly with little variance or the grease will leak out between the coupler and the fitting. Also, the coupler must have positive pressure from the operator against the zerk fitting to ensure the efficient transfer of grease through the fitting. In other words, the operator must push the grease gun against the zerk fitting throughout the lubrication process. If the zerk fitting is in a hard to reach location, maintaining accurate placement of the grease gun coupler and positive pressure during the lubrication procedure, is difficult and usually transfers an insufficient amount of lubricant.
Those skilled in the art are aware of various extensions and couplers for grease guns. Mostly, such couplers or extensions slip over the fitting with a snap action. Generally, these couplings are easily dislodged and inadvertently release from the fitting if the coupler is slightly twisted or moved to an angle, slightly off perpendicular, on the zerk fitting. More often than not, the coupling must be applied to the zerk fitting in such a position that it cannot be held onto the fitting as required.
Positive lock couplings are known in the art, but the design is usually complicated and involves multiple mechanical parts that must work together to insure a positive lock and efficient transfer of lubricant. Usually, in these cases, the procedure for attaching the coupler to the fitting is complicated, unwieldy and the costs to manufacture are relatively high.
Poor maintenance procedures caused by hard to reach zerk fittings can cause very expensive damage due to poorly lubricated mechanical parts. Most often it is not the fault of the operator as the zerk fitting is in a hard to reach and usually hard to see location. The fittings in hard to reach locations may be dangerous to the operator. An operator may be required to blindly reach into the location to make the connection between the zerk and the grease gun. If the equipment engages during the time the operator is trying to connect the grease gun, at the very least the operator's hands are at risk and maybe his life.
It would be desirable, therefore, to provide a coupler for a grease gun, with a minimum number of parts, that would ensure positive connection to a zerk fitting regardless of the location of the fitting and without the need for positive pressure, during the lubrication procedure, from the operator. It would also be desirable that the device be easy to operate.